Means for making conduits



T. E. MURRAY July 13,1926. 'im' MEANS FOR MAKING CONDUITS Filed April' 2o, 192s Patented July 13, 1926.

THOMAS" E. MURRAY, OF BROOKLYN,Y NEW YORK.

MEANs Fon MAKING coNnUITs.

Application filed April 20, 1923. Serial No. 633,410.

This invention relates to improvements in the method `of making conduits of moldable material such as concrete, cement, clay, plaster and the like, and also to improve` ments `in cores used-in molding or casting such materials.

The invention aims to provide a methodV whereby a core of comparatively soft yielding material may be used without danger of collapsing or distorting the core while the concrete is being dumped into the mold.

The invention is illustrated in the accompanying drawings inwhich Fig. 1 is a transverse section through a mold supporting a plurality of cores made of bibulousmaterial and -carried by inner metal shells.

Fig. 2 is an enlarged longitudinal section of a portion of a core embodying my invention; t l

Figs. 3, 4, and 5 illustrate steps in making a conduit according to my method;

Fig. 6 illustrates a joint for connecting adjacent sections of the core lining.

yReferring to the drawings, the cores 10' are supported yon suitable cross pieces 12 Sei Vcured at the ends of the false work or form 14, forming part of the mold. The forms or false work may be of any suitablev material and may take different shapes according to requirements, the construction shown being merely illustrative.

The cores 10 are of improved construction and each comprises a comparatively'l still inner shell 16 formed of any suitable material, preferablylof steel or comparatively thin sheet iron, andin some cases ordinary steel tubing oriron pipe can be used for the purpose. The shell 16 is located Within a compara-tively soft yielding sheath 18 which may be made of various material as, for example, paper or cardbo'ird formed by spirally winding on a suitab e mandrel. loosely over the shell 16 so that the shell can be withdrawn after the material has,

been molded or cast, as will hereinafter appear.

The invention is particularly useful in forming conduits of great length for the accommodation` of electric wiring used below the surface of the earth, such as under street pavements and in subways, tunnels, viaducts and similar locations.

As disclosed in previous Murray patents, it is particularly advantageous to utilize cores of bibulous material in forming The paper sheath 18 fitsv molded conduits because such material quickly absorbs moisture from the concrete throughout the surface of the molded conduit and hence quickens the setting of the concrete or other moldable Surface adjacent to the core.

A diiiiculty, howeverfhas been experienced in using paper cores'. This is a liability of Such cores being dented or fractured when the material is cast or dumped around the core. Of course where the core is dented or fractured, inequalities will appear in the surfaceof the conduit, and such inequalif ties mterfere with the fishing of' wires or.

cables through the conduit and also interfere with. the removal ofthe paper core from the conduit. l

By use of my improved coreand method these difiiculties are overcome. In carrying out the' method I lirst place the aper sheath over the metallic shell. This orms a core such as indicated at 10. Thecore or cores are then separately supported on crossbeams or other false work, and the concretedumped into the form as shown in Fig. 1. As thus arranged it is apparent that stones or gravel striking the paper sheath 18 cannot dent or puncture th same because of the resistance of the shell 16. After the material has been dumped into the form and the core is covered,- the shells 16 are immediately removed, the paper cores being of sufficient sti'fnessto retain their shape,

it being apparent .that after the cores arer covered the pressure is substantially equalized throughout the surface of the paper core. By immediately withdrawing the steel shells 16 they are available for use again in other locations. Fig. 1, the shells have been withdrawn from Y the sheaths 18 leaving only thepaper cores for` the two bottom conduitsa/YThese same steel shells can be used in for/ming the cores 10 forthe two upper 'conduits as will be appreciated.

The conduits are usually of great length and, for ease in handling, the paper sheaths For example, in

and steel shells are'made in comparatively` short sections. For joining the adjacent steel tubular sections, Ihave shown 1n Fig.

6 a'sleeve 20 secured tothe end of one section and telescopically engaging the adjacent end ofl a mating section. The sleeve being formed with a bayonet slot 22 .for engagement with a lug 24. With this arrangement it is apparent that the sections can be readily coupled together or disconnected as desired.

In a co-pending application Serial Number 633,408, filed concurrently herewith, I

have shown and described a preferred means and method for joining and disconnecting the inner sections of the core, and this .detail, therefore, will not be described or claimed herein.

The steps of the method are shown graphically in Figs. 3, 4 and 5, Fig. 3 showing a core comprising a steel shell 16 sheathed with a removable paper covering 18 and e'mbedded in a mass of concrete, 26. shows the paper core after the inner metallic shell has been removed and Fig. 5 shows the conduit after the removal of the paper sheath.

The paper sheath 18 may Le provided with an exterior spirally Wound member adaped to collapse the core after it has absorbed the moisture from the concrete mass,

and after the latter has set suiiiciently.

The means for collapsing and withdrawing the paper tube is not shown and described specically herein as the same is of known construction and covered by previous Murray patents.

Though I have described with great particularity a certain specific core and steps Fig. 4-

in the method forming conduits, it is not to be construed that I am limited thereto, as changes may be made by those skilled in the art without departing from the invention as defined in the appended claims.

That I claim is:

1. A core for the purposes described comprising an outer member of comparatively soft yielding material strong enough to support the surrounding plastic material after the latter has been cast in place and non` contractible inner tubular member having suicient inherent stiffness to support the outer member during the casting operation to prevent distortion thereof.

2. A core for the purposes described com prising an outer member of comparatively soft yielding material strong enough to sup- -portthe surrounding plastic material after the latter has been cast in lace and innertubular member having su cient inherent stitfness' to support the outer member during the casting operation to prevent distortion thereof, the inner member fitting loosely within the outer member so as to be easily inserted into and withdrawn therefrom.

In witness whereof, I have hereunto signed vmy name.

THOMAS EQMURRAY. 

